The stator or the rotor of electrical machines generally comprises teeth and a core back. The function of the teeth is to lead magnetic flux induced in the teeth by a coil arranged round the teeth and, thus, the teeth increases the efficiency of the interaction between the stator and a rotor, in respect of a stator or a rotor having no teeth. The core back is arranged to magnetically connect the teeth to each other in order to provide a flux feedback loop having low reluctance, i.e. it may be seen as closing the magnetic circuit generating flux for interaction with a rotor.
The stator cores of electrical machines have generally been made of solid soft magnetic material, e.g. iron. One problem with these types of stator cores is that eddy currents are induced in the stator core. To reduce this problem with eddy currents the stator cores of today are made of sheets of soft magnetic material that is stacked together and electrically insulated from each other or of iron powder being electrically insulated.
In U.S. Pat. No. 6,445,105 there is shown an axial flux machine having a core back made of laminations to which teeth of molded iron are attached and directed in an axial direction.